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</a></div> <!----></nav>  <ul class="sidebar-links"><li><a href="/docs/js/" aria-current="page" class="sidebar-link">介绍</a></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>JavaScript</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/docs/js/base/type-of-data.html" class="sidebar-link">JS 的数据类型</a></li><li><a href="/docs/js/base/object.html" class="sidebar-link">JS 对象的常用属性</a></li><li><a href="/docs/js/base/function.html" class="sidebar-link">函数 &amp; 原型链</a></li><li><a href="/docs/js/base/dom-api.html" class="sidebar-link">DOM API 总结</a></li><li><a href="/docs/js/base/node-api.html" class="sidebar-link">节点 API 总结</a></li><li><a href="/docs/js/base/node-list.html" class="sidebar-link">节点中的伪数组</a></li><li><a href="/docs/js/base/dom-operate-across-threads.html" class="sidebar-link">DOM 操作跨线程</a></li><li><a href="/docs/js/base/create-jquery.html" class="sidebar-link">jQuery 中的链式操作</a></li><li><a href="/docs/js/base/plugin.html" class="sidebar-link">JavaScript 插件 / 库</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading open"><span>ES6</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/docs/js/es6/scope.html" class="sidebar-link">作用域</a></li><li><a href="/docs/js/es6/new-object.html" aria-current="page" class="active sidebar-link">新版对象</a></li><li><a href="/docs/js/es6/anatomy-assignment.html" class="sidebar-link">参数处理 &amp; 解构赋值</a></li><li><a href="/docs/js/es6/new-string.html" class="sidebar-link">新版字符串</a></li><li><a href="/docs/js/es6/module-use.html" class="sidebar-link">ES6 模块化</a></li><li><a href="/docs/js/es6/promise-usage.html" class="sidebar-link">Promise</a></li><li><a href="/docs/js/es6/await-and-async.html" class="sidebar-link">async 和 await 的用法</a></li><li><a href="/docs/js/es6/symbol-iterate-generate.html" class="sidebar-link">Symbol &amp; 迭代器 &amp; 生成器</a></li><li><a href="/docs/js/es6/arrow-function.html" class="sidebar-link">箭头函数</a></li><li><a href="/docs/js/es6/new-api.html" class="sidebar-link">ES6 新增 API</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>JavaScript 进阶</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/docs/js/part/ajax-use.html" class="sidebar-link">AJAX</a></li><li><a href="/docs/js/part/cross-domain.html" class="sidebar-link">跨域 &amp; CORS &amp; JSONP</a></li><li><a href="/docs/js/part/browser-storage.html" class="sidebar-link">浏览器模型</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>JS 小记</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/docs/js/note/project.html" class="sidebar-link">JavaScript 搭建项目</a></li><li><a href="/docs/js/note/js-garbage.html" class="sidebar-link">JS 的缺陷</a></li><li><a href="/docs/js/note/setInterval-a-setTimeout.html" class="sidebar-link">使用 setTimeout 实现 setInterval</a></li><li><a href="/docs/js/note/array-deduplica.html" class="sidebar-link">数组去重</a></li><li><a href="/docs/js/note/download-file.html" class="sidebar-link">使用 JS 下载文件</a></li><li><a href="/docs/js/note/top-nav.html" class="sidebar-link">设置导航动态显示 / 隐藏</a></li><li><a href="/docs/js/note/anchor-transition.html" class="sidebar-link">JS 实现点击锚点过渡效果</a></li><li><a href="/docs/js/note/data-list.html" class="sidebar-link">数据处理</a></li></ul></section></li></ul> </div></div><div class="el-scrollbar__bar is-horizontal"><div class="el-scrollbar__thumb" style="width:0;transform:translateX(0%);ms-transform:translateX(0%);webkit-transform:translateX(0%);"></div></div><div class="el-scrollbar__bar is-vertical"><div class="el-scrollbar__thumb" style="height:0;transform:translateY(0%);ms-transform:translateY(0%);webkit-transform:translateY(0%);"></div></div></div></aside> <main class="page"> <div class="re-page-top"><h1 class="title"><span>新版对象</span></h1> <div class="re-page-index"><div class="page-index-title"><span class="open-catalog"><svg aria-hidden="true" class="icon arrow-right"><use xlink:href="#icon-bold-right"></use></svg> <span class="text">目录</span></span></div> <div class="page-index-content"><div class="page-catalog" style="display:none;"><div class="synopsis-wrap"><ul class="synopsis-ul"><li class="synopsis-li"><a href="/docs/js/es6/new-object.html#创建对象" class="synopsis-link">创建对象</a><ul class="synopsis-ul"><li class="synopsis-li"><a href="/docs/js/es6/new-object.html#之前的创建方法" class="synopsis-link">之前的创建方法</a></li><li class="synopsis-li"><a href="/docs/js/es6/new-object.html#es6新增方法" class="synopsis-link">ES6新增方法</a></li></ul></li><li class="synopsis-li"><a href="/docs/js/es6/new-object.html#对象赋值" class="synopsis-link">对象赋值</a></li><li class="synopsis-li"><a href="/docs/js/es6/new-object.html#使用变量作为对象属性名" class="synopsis-link">使用变量作为对象属性名</a></li><li class="synopsis-li"><a href="/docs/js/es6/new-object.html#设置对象读取-写入权限" class="synopsis-link">设置对象读取/写入权限</a></li><li class="synopsis-li"><a href="/docs/js/es6/new-object.html#实现-a-1-a-2-a-3-结果为-true" class="synopsis-link">实现 a === 1 &amp;&amp; a === 2 &amp;&amp; a === 3 结果为 true</a></li><li class="synopsis-li"><a href="/docs/js/es6/new-object.html#对象浅拷贝" class="synopsis-link">对象浅拷贝</a></li><li class="synopsis-li"><a href="/docs/js/es6/new-object.html#设置对象原型" class="synopsis-link">设置对象原型</a></li></ul></div></div></div></div></div> <div class="theme-default-content content__default"><h2 id="创建对象"><a href="#创建对象" class="header-anchor">#</a> 创建对象</h2> <h3 id="之前的创建方法"><a href="#之前的创建方法" class="header-anchor">#</a> 之前的创建方法</h3> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">var</span> a1 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Object</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token keyword">var</span> a2 <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
</code></pre></div><blockquote><p>上面的两种方法创建的对象都有对象的原型链属性</p></blockquote> <h3 id="es6新增方法"><a href="#es6新增方法" class="header-anchor">#</a> ES6新增方法</h3> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> b1 <span class="token operator">=</span> Object<span class="token punctuation">.</span><span class="token function">create</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token comment">// 没有对象的原型链</span>
<span class="token keyword">let</span> b2 <span class="token operator">=</span> Object<span class="token punctuation">.</span><span class="token function">create</span><span class="token punctuation">(</span><span class="token class-name">Object</span><span class="token punctuation">.</span>prototype<span class="token punctuation">)</span> <span class="token comment">// 传入对象的原型链</span>
</code></pre></div><blockquote><p>ES6方法创建的对象，只有在传入 <code>Object.prototype</code> 是才会生成具有对象原型链的空对象
当传入的值为 null 时，生成的对象是不具有原型链的（也就是真正的空对象）</p></blockquote> <p><strong>案例</strong></p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Object</span><span class="token punctuation">(</span><span class="token punctuation">)</span>                     <span class="token comment">// ES5 - 有原型链的空对象</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> Object<span class="token punctuation">.</span><span class="token function">create</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">)</span>              <span class="token comment">// ES6 - 什么都没有的空对象(真正的空对象)</span>
<span class="token keyword">var</span> c <span class="token operator">=</span> Object<span class="token punctuation">.</span><span class="token function">create</span><span class="token punctuation">(</span><span class="token class-name">Object</span><span class="token punctuation">.</span>prototype<span class="token punctuation">)</span>  <span class="token comment">// ES6 - 有原型链的空对象</span>
<span class="token keyword">var</span> d <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>                               <span class="token comment">// ES5 - 有原型链的空对象</span>
</code></pre></div><h2 id="对象赋值"><a href="#对象赋值" class="header-anchor">#</a> 对象赋值</h2> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> a <span class="token operator">=</span> <span class="token number">1</span>
<span class="token keyword">let</span> b <span class="token operator">=</span> <span class="token number">2</span>
<span class="token keyword">let</span> object <span class="token operator">=</span> <span class="token punctuation">{</span> a<span class="token operator">:</span> a<span class="token punctuation">,</span> b<span class="token operator">:</span> b <span class="token punctuation">}</span> <span class="token comment">// 之前的写法</span>
<span class="token keyword">let</span> object <span class="token operator">=</span> <span class="token punctuation">{</span> a<span class="token punctuation">,</span> b <span class="token punctuation">}</span> <span class="token comment">// ES6写法</span>
</code></pre></div><h2 id="使用变量作为对象属性名"><a href="#使用变量作为对象属性名" class="header-anchor">#</a> 使用变量作为对象属性名</h2> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> name <span class="token operator">=</span> <span class="token string">'a'</span>
<span class="token keyword">let</span> object <span class="token operator">=</span> <span class="token punctuation">{</span>
    <span class="token punctuation">[</span>name<span class="token punctuation">]</span><span class="token operator">:</span> <span class="token number">1</span>
<span class="token punctuation">}</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>object<span class="token punctuation">)</span> <span class="token comment">// 输出 {a: 1}</span>
</code></pre></div><p>对象属性名可以做简单的运算</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> n <span class="token operator">=</span> <span class="token number">2</span>
<span class="token keyword">let</span> a <span class="token operator">=</span> <span class="token punctuation">{</span>
    <span class="token punctuation">[</span>n<span class="token operator">*</span>n <span class="token operator">+</span> n<span class="token operator">/</span>n <span class="token operator">+</span> n<span class="token operator">/</span><span class="token number">3</span><span class="token punctuation">]</span><span class="token operator">:</span> <span class="token number">1</span>
<span class="token punctuation">}</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token comment">// 输出 {5.666666666666667: 1}</span>
</code></pre></div><h2 id="设置对象读取-写入权限"><a href="#设置对象读取-写入权限" class="header-anchor">#</a> 设置对象读取/写入权限</h2> <p>在对象内部可以添加两个方法：get方法，负责读取时做的操作。set方法，负责修改时做的操作。</p> <p>通过这两个方法可以对对象的属性做访问/修改的限制，如下</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> age <span class="token operator">=</span> <span class="token number">18</span>
<span class="token keyword">let</span> o <span class="token operator">=</span> <span class="token punctuation">{</span>
    <span class="token keyword">get</span> <span class="token function">age</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">return</span> age
    <span class="token punctuation">}</span><span class="token punctuation">,</span>
    <span class="token keyword">set</span> <span class="token function">age</span> <span class="token punctuation">(</span><span class="token parameter">value</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">if</span> <span class="token punctuation">(</span>value <span class="token operator">&lt;</span> <span class="token number">100</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
            age <span class="token operator">=</span> value
        <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
            age <span class="token operator">=</span> <span class="token number">100</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>age<span class="token punctuation">)</span>   <span class="token comment">// 输出 18</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>o<span class="token punctuation">.</span>age<span class="token punctuation">)</span> <span class="token comment">// 输出 18</span>
o<span class="token punctuation">.</span>age <span class="token operator">=</span> <span class="token number">1000</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>o<span class="token punctuation">.</span>age<span class="token punctuation">)</span> <span class="token comment">// 输出 100</span>
</code></pre></div><h2 id="实现-a-1-a-2-a-3-结果为-true"><a href="#实现-a-1-a-2-a-3-结果为-true" class="header-anchor">#</a> 实现 <code>a === 1 &amp;&amp; a === 2 &amp;&amp; a === 3</code> 结果为 true</h2> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> i <span class="token operator">=</span> <span class="token number">0</span>
<span class="token comment">/* 给 window 添加一个属性，属性名是 a，a 有一个 get 函数 */</span>
Object<span class="token punctuation">.</span><span class="token function">defineProperty</span><span class="token punctuation">(</span>window<span class="token punctuation">,</span> <span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
    <span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        i<span class="token operator">+=</span><span class="token number">1</span>
        <span class="token keyword">return</span> i
    <span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
a <span class="token operator">===</span> <span class="token number">1</span> <span class="token operator">&amp;&amp;</span> a <span class="token operator">===</span> <span class="token number">2</span> <span class="token operator">&amp;&amp;</span> a <span class="token operator">===</span> <span class="token number">3</span> <span class="token comment">// 输出 true</span>
</code></pre></div><div class="custom-block info"><p class="custom-block-title">原理</p><p>控制全局变量 a 的读取过程，每次访问 a 的值都会改变</p></div><h2 id="对象浅拷贝"><a href="#对象浅拷贝" class="header-anchor">#</a> 对象浅拷贝</h2> <p>之前的写法</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> obj1 <span class="token operator">=</span> <span class="token punctuation">{</span> a<span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span> b<span class="token operator">:</span> <span class="token number">2</span><span class="token punctuation">,</span> c<span class="token operator">:</span> <span class="token number">3</span> <span class="token punctuation">}</span>
<span class="token keyword">let</span> obj2 <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
<span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> key <span class="token keyword">in</span> obj1<span class="token punctuation">)</span><span class="token punctuation">{</span>
    obj2<span class="token punctuation">[</span>key<span class="token punctuation">]</span> <span class="token operator">=</span> obj1<span class="token punctuation">[</span>key<span class="token punctuation">]</span>
<span class="token punctuation">}</span>
obj2 <span class="token operator">===</span> obj1
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj1<span class="token punctuation">)</span> <span class="token comment">// 输出 {a: 1, b: 2, c: 3}</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj2<span class="token punctuation">)</span> <span class="token comment">// 输出 {a: 1, b: 2, c: 3}</span>
obj2<span class="token punctuation">.</span>a <span class="token operator">=</span> <span class="token number">100</span> <span class="token comment">// obj2.a 为 100</span>
obj1<span class="token punctuation">.</span>a <span class="token comment">// obj1.a 为 1</span>
</code></pre></div><p>ES6浅拷贝（1）</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> obj1 <span class="token operator">=</span> <span class="token punctuation">{</span>a<span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span> b<span class="token operator">:</span> <span class="token number">2</span><span class="token punctuation">,</span> c<span class="token operator">:</span> <span class="token number">3</span><span class="token punctuation">}</span>
<span class="token keyword">let</span> obj2 <span class="token operator">=</span> Object<span class="token punctuation">.</span><span class="token function">assign</span><span class="token punctuation">(</span><span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">,</span> obj1<span class="token punctuation">)</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj2<span class="token punctuation">)</span> <span class="token comment">// {a: 1, b: 2, c: 3}</span>
</code></pre></div><p>ES6浅拷贝（2）</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> obj1 <span class="token operator">=</span> <span class="token punctuation">{</span> a<span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span> b<span class="token operator">:</span> <span class="token number">2</span><span class="token punctuation">,</span> c<span class="token operator">:</span> <span class="token number">3</span> <span class="token punctuation">}</span>
<span class="token keyword">let</span> obj2 <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token operator">...</span>obj1<span class="token punctuation">}</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj2<span class="token punctuation">)</span>
</code></pre></div><p>ES6对象案例</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> obj1 <span class="token operator">=</span> <span class="token punctuation">{</span> a<span class="token operator">:</span> <span class="token number">1</span> <span class="token punctuation">}</span>
<span class="token keyword">let</span> obj2 <span class="token operator">=</span> <span class="token punctuation">{</span> b<span class="token operator">:</span> <span class="token number">2</span> <span class="token punctuation">}</span>
<span class="token keyword">let</span> obj3 <span class="token operator">=</span> <span class="token punctuation">{</span> c<span class="token operator">:</span> <span class="token number">3</span> <span class="token punctuation">}</span>
<span class="token keyword">let</span> aa <span class="token operator">=</span> <span class="token number">1</span>
<span class="token keyword">let</span> bb <span class="token operator">=</span> <span class="token number">2</span>
<span class="token keyword">let</span> obj4 <span class="token operator">=</span> <span class="token punctuation">{</span>
    <span class="token operator">...</span>obj1<span class="token punctuation">,</span> <span class="token operator">...</span>obj2<span class="token punctuation">,</span> <span class="token operator">...</span>obj3<span class="token punctuation">,</span> aa<span class="token punctuation">,</span> bb<span class="token punctuation">,</span> <span class="token keyword">get</span> <span class="token function">x</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span> <span class="token keyword">return</span> <span class="token string">'hi'</span> <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
obj4
</code></pre></div><blockquote><p>在 obj4 中添加 obj1 obj2 obj3 对象的属性，并添加变量 aa bb 为 obj4 的属性，设置属性x的访问值为 'hi'</p></blockquote> <h2 id="设置对象原型"><a href="#设置对象原型" class="header-anchor">#</a> 设置对象原型</h2> <p>使用 <code>a = Object.create(b)</code> 的方法可以给对象添加新的原型链。</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> a <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
a<span class="token punctuation">.</span>__proto__
a<span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment">// 输出 &quot;[object Object]&quot;</span>
a<span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment">// 输出 {}</span>
a<span class="token punctuation">.</span>__proto__ <span class="token operator">===</span> <span class="token class-name">Object</span><span class="token punctuation">.</span>prototype <span class="token comment">// 输出 true</span>
<span class="token class-name">Object</span><span class="token punctuation">.</span>prototype
<span class="token keyword">let</span> b <span class="token operator">=</span> <span class="token punctuation">{</span>
    <span class="token function">sayHi</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'hi'</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
a <span class="token operator">=</span> Object<span class="token punctuation">.</span><span class="token function">create</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span> <span class="token comment">// a的原型指向b</span>
a<span class="token punctuation">.</span>__proto__ <span class="token operator">===</span> b <span class="token comment">// 输出 true</span>
</code></pre></div><p>访问对象原型链</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> a <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
a<span class="token punctuation">.</span>__proto__
Object<span class="token punctuation">.</span><span class="token function">getPrototypeOf</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token comment">// 推荐写法</span>
</code></pre></div><p>查询对象的属性是否存在</p> <div class="language-js extra-class"><pre class="language-js"><code>a<span class="token punctuation">.</span><span class="token function">hasOwnProperty</span><span class="token punctuation">(</span><span class="token string">'indexOf'</span><span class="token punctuation">)</span>
</code></pre></div><p>使用 <code>hasOwnProperty('__proto__')</code> 无法查看原型属性</p> <div class="language-js extra-class"><pre class="language-js"><code>a<span class="token punctuation">.</span><span class="token function">hasOwnProperty</span><span class="token punctuation">(</span><span class="token string">'__proto__'</span><span class="token punctuation">)</span> <span class="token comment">// 输出 false</span>
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